GI embryology

Question 1

What do the liver, gallbladder and pancreas develop from?

Answer 1

diverticulum of the cranial half of the duodenum

Question 2

What does the would-be liver look like in week 3?

Answer 2

In week 3, the liver appears as an out-pocketing of the future duodenum – hepatic diverticulum (liver bud)

Question 3

What is the septum transversum?

Answer 3

future diaphragm

Question 4

What do endodermal cells differentiate into?

Answer 4

hepatocytes (parenchyma) of liver

Question 5

What are haematopoietic, Kupffer cells and connective tissue derived from ?

Answer 5

mesoderm of the septum transversum

Question 6

What happens when the liver becomes too large to be contained within the septum transversum

Answer 6

It protrudes into the ventral mesentery

Question 7

What does the protrusion of the liver do to the structure of the ventral mesentary?

Answer 7

This divides the ventral mesentery into 2 parts:
Falciform ligament
Lesser omentum

Question 8

The mesoderm on the surface of the liver differentiates into visceral peritoneum except on what ?

Answer 8

the cranial surface

Question 9

The cranial surface remains in contact with the septum transversum and becomes the ________?

Answer 9

bare area of the liver

Question 10

Around margins of bare area, peritoneum reflects to form the ________?

Answer 10

coronary ligament

Question 11

Coronary ligament ultimately ends at the lateral edges of the liver as the left and right _________?

Answer 11

triangular ligaments

Question 12

What percentage of total body weight is the liver at 10 weeks?

Answer 12

10%

Question 13

What percentage is the liver of total body weight at birth?

Answer 13

5%

Question 14

Why is the liver so large in the foetus?

Answer 14

it’s importance in haematopoiesis

Question 15

Where does haematopoisis shift to after birth?

Answer 15

the bone marrow

Question 16

What does a ventral outgrowth of the bile duct form at the end of week 3?

Answer 16

the gallbladder and cystic duct

Question 17

At what week does the liver start to produce bile?

Answer 17

week 12

Question 18

What is the first dark green bowel movement o a newborn called?

Answer 18

meconium

Question 19

Why are 60% of full term infants jaundiced?

Answer 19

The immature liver does not have sufficient glucuronosyltransferase to conjugate bilirubin

Question 20

What is kernicterus and how is it treated

Answer 20

Excess unconjugated bilirubin crosses the blood-brain barrier and causes brain damage

Phototherapy oxidises bilirubin to a water soluble form that can be easily excreted by the newborn and does not contribute to kernicterus
(Blue light)

Question 21

What does failure of either duct to recanalise lead to?

Answer 21

biliary atresia

Question 22

How common is biliary atresia?

Answer 22

1 in 15,000 births

Question 23

What are the symptoms of biliary atresia?

Answer 23

Causes symptoms that are initially indistinguishable from neonatal jaundice but do not respond to phototherapy

Question 24

How are multiple gallbladders caused? (2 or 3)

Answer 24

Caused by extra endodermal outpocketing during weeks 5 and 6

Question 25

The dorsal bud appears in week __ as an outpocketing of the duodenum that extends into the _______ _______.

Answer 25

The dorsal bud appears in week 3 as an outpocketing of the duodenum that extends into the dorsal mesentery

Question 26

As duodenum rotates ___ clockwise (as stomach rotates) the ventral bud carried _____ along with bile duct

Answer 26

As duodenum rotates 90° clockwise (as stomach rotates) the ventral bud carried dorsally along with bile duct

Question 27

During what week do the ventral and dorsal pancreatic buds fuse?

Answer 27

week 6

Question 28

What does the ventral pancreatic bud form?

Answer 28

Uncinate process

Question 29

At which point does the main pancreatic duct enter the duodenum?

Answer 29

at major duodenal papilla (Ampulla of Vater)

Question 30

Where does the accessory pancreatic duct enter?

Answer 30

minor duodenal papilla

Question 31

What are the implications of a bilobed pancreatic bud migrating dorsally to surround the duodenum

Answer 31

This can compress the duodenum causing gastrointestinal obstruction

Question 32

Where can ectopic pancreatic tissue be found?

Answer 32

Can be found in areas ranging from distal oesophagus to tip of primary intestinal loop.

Most frequently in duodenum or stomach mucosa

Question 33

What are symptoms of ectopic pancreatic tissue?

Answer 33

asymptomatic

Large lesions may cause obstruction, ulceration or haemorrhage

Question 34

What layer is the spleen derived from?

Answer 34

mesoderm